1. Field of the Invention
The present invention relates to improved devices for on-board addition of performance additives to fuel systems of internal combustion (“IC”) engines.
2. Description of Related Art
Fuel performance additives are well known for the treatment of engine fuels. The additives can be designed to improve the chemical properties of the fuel such as reducing oxidation, improving stability, reducing corrosivity, lowering pour point, lowering cloud point and eliminating or reducing biological degradation. Fuel additives can also be used to improve the performance properties of the fuel leading to reduction in emissions, increased fuel economy and improved combustion efficiency. The term fuel additives can include single additives, multiple additives and/or additive packages.
It is desirable that the concentration of the additives, depending on desired performance, be maintained in close and critical range. Additive levels in excess of the critical range can be detrimental, especially with respect to the possible formation of sludge, varnishes, gums, and other potentially hazardous substances that can reduce the performance of the engine and can even harm the engine itself. High treatment levels are also non-economical.
Additive levels less than the critical treatment amount can result in lack of engine performance leading, among other things, to fuel degradation and possibly even engine damage. Poor engine operation can also be non-economical.
Currently, fuel additives are typically added to the fuel at large fuel terminals to bulk storage tanks, tank trucks, rail cars or other storage receptacles. The fuel is added by a process known as “splash blending” which means the additives are added as the fuel is being loaded into the receptacle. The process relies on the splashing of the liquids to effect mixing.
Splash blending can also be used to mix the additive with the fuel at on-site tanks. In this case the additive is added to, for example, a bulk fuel tank or bunker tank located at the site of end-use. The splashing of the liquids mixes the additives as the tank is being filled from a fuel distribution vehicle or pipeline. Fuel distribution vehicles can include trucks, rail cars, barges or the like.
Splash blending can similarly be used to additize fuel in on-board bulk tanks or in on-board direct use tanks. The term “on-board” refers to a location on a vessel being driven by the IC engine using the additized fuel. Suitable vessels can include, but are not limited to, railroad locomotives and various marine vessels such as tug boats and barges. The term “direct use tank” refers to the fuel tank that directly feeds the IC engine.
Splash blending is convenient and requires very little capital investment to implement but has several major disadvantages. For one, there is little or no control over the actual mixing process. Lack of positive mixing control could lead to low or otherwise improper additive concentrations. Improper additive concentrations can result in engine damage. Also, there is little or no flexibility to vary additive concentrations to possibly optimize fuel performance. Once the bulk fuel has been additized it would be very difficult to increase the additive concentration. It would be difficult for the additive to mix in with the fuel other than possibly through normal diffusion which is a lengthy and unreliable process. Further, the only way to reduce the additive concentration would be to further dilute the additized tank with more fuel. This also would not be practical.
Also, the additized fuel may not be available in remote locations. This is particularly applicable, for example, in the operation of locomotives and marine vessels. It is possible, and even likely, that refueling may be required in locations and areas where the additive or additized fuel is not available. Additized fuel stored for extended periods of time can degrade, become unstable or otherwise lose effectiveness. There is no way, other than actual chemical analysis, to assure efficacy or concentrations of the pre-additized fuel or additized fuel stored in bulk tanks. Furthermore, continuous chemical analysis is not practical or economical.
Bulk fuel blending methods, other than splash blending, have been and are continuing to be used in industry. Although some fuel blending techniques, such as the utilization of mechanical and in-line agitation, are improvements in mixing control over splash blending, they still suffer much of the other splash blending disadvantages listed above.
Therefore, an improved system and method to enhance the quality and performance of fuel used in IC engines, particularly on board locomotives and marine vessels, is needed. This improved system should preferably include the addition of chemical and performance enhancing additives to the fuel in a manner that is highly accurate, is highly flexible, especially with respect to the ability to vary additive concentrations, can deliver the fuel additives on demand, provide a positive verification of efficacy, and is available in all locations.